The invention relates to a single cell for a battery with electrodes (preferably electrode foils) arranged inside a cell housing, wherein a current output lug is electrically connected to each electrode and to a pole, and wherein at least electrodes of different polarities are separated and insulated from each other by a separator (preferably a separator foil). Such a battery is known, for example in energy technology, and especially to support battery-operated vehicle technology.
Especially single cells as known from German patent document DE 42 40 339 C1, which are designed as flat cells, are formed as electrode foils, aluminum and copper foils, coated with electrochemically active materials. The electrode foils are combined to form an electrode stack, wherein the single electrode foils are separated from each other electrically and also spatially by a separator, preferably a foil. A current output lug, which is guided through the cell housing, is welded to the electrode foil for a contacting of an electrode foil to the outside. As the cell housing of a single cell is usually formed of metal, preferably aluminum, the current output lugs have to be insulated electrically amongst others in the feedthrough region.
The tightness of the cell housing in the feedthrough region can only be manufactured with difficulty and in a very elaborate manner. This problem especially relates to the compression strength and the sealing against humidity. A humidity entry thus has to be seen as a difficult problem, which can be solved in a particularly elaborate manner.
One object of the invention is to provide a single cell of a battery, where the tightness of the cell housing is improved and where the production costs are preferably reduced.
This and other objects and advantages are achieved by the single cell of a battery according to the invention, which comprises electrodes, preferably electrode foils, arranged within a housing. A current output lug is thereby arranged at each electrode in an electrically conductive manner. At least electrodes of different polarity are separated in an electrically insulating manner by means of a separator (preferably a separator foil), and the current output lug is connected to a pole in an electrically conductive manner. According to the invention, each pole of the single cell is electrically connected to an electrically conductive region of an outer side of the cell housing, and designed as a lug-type extension piece of the outer side as a so-called pole lug.
By the direct contacting of the poles to regions which are electrically insulated from each other of at least one outer side of the cell housing, preferably two flat sides of the cell housing (preferably a flat cell), metallic cell walls extending partially beyond the cell body can now be used as pole lugs. It is thus possible for the electrical connection of several cells to a battery, to connect these preferably lug-type extension pieces for the purpose of an electrical series connection especially by means of spot welding.
For increasing the handling safety outside the pole lugs housing side walls are electrically insulated especially with coatings and/or thin foils in a convenient manner.
In an advantageous manner, special cross sectional surfaces of the pole lugs can be realized by molds for example for increasing the current capacity, but also for increasing the stability.
In a special manner, a pole lug is connected monolithically for this to its associated region of the corresponding outer side.
The pole lugs of a single cell are arranged at a single narrow side of the cell housing in a special manner and especially at opposite corner regions, wherein the pole lugs project with the same alignment from this narrow side for an easier accessibility.
To enable a simple and secure connection of several single cells, the pole lugs conveniently have a measured width in the direction of their common arrangement which is smaller than half (preferably smaller than a fifth and especially preferred smaller than a tenth) of the corresponding extension of the associated narrow side.
According to an advantageous further development of the invention, with several electrodes, especially electrode foils, the associated current output lugs of a single cell are welded and/or compressed with each other to a pole. These or the pole can thereby be guided from the interior of the single cell to the outside without elaborate sealing measures. The contacting thereby especially takes place by means of welding an associated outer side, so as to contact the electrode foils in the interior with the outside.
In a special manner, an edge region of the respective electrode foil guided to the outside of the electrode stack is used as the current output lug, whereby an elaborate contacting of electrode foils and current output lug is omitted. This type of contacting is at the same time very safe against at least many, especially outer influences such as impacts or vibrations.
Handling of the single cell is eased or designed in a more secure manner by inserting an electrically insulating plastics foil, especially a frame circumferentially on the edge.
In a further development of the invention, an electrically insulating frame running circumferentially around the edge is arranged between two electrically conductive flat sides of the cell housing, which frame has two material recesses insulated from each other and spaced from each other. The current output lugs of respectively one polarity are arranged in these material receptions. Advantageously, the clear height measured in the direction of the stacking of the electrodes of a material recess is smaller or the same as the corresponding extension of the associated current output lugs stacked above each other in an uninfluenced manner, and their depth measured parallel to the flat side of an electrode foil is larger or the same as the corresponding extension of the associated current output lugs. The current output lugs are hereby held securely in the material recesses and can be compressed with these in an electrically conductive manner with an especially tight connection between the frame and the outer/flat sides.
According to a further embodiment of the invention, the electrical connection between the cell housing and a “+” or “−” pole at the electrode stack is produced only during and especially after the assembly of the cell housing, and namely from the outside through a welding and/or pressing method, in a preferred manner by means of a laser beam welding method.
In a preferred manner, the housing wall of the respective outer side and further in the depth the current output lugs of the electrode stack can be melted on partially during a welding method, whereby a material-fit connection can be produced.
According to a further advantageous development of the invention, a weld seam comprises all current output lugs or passes through these, seen in the direction of the stacking of the electrodes.
According to a further development of the invention, a weld seam comprises, seen in the direction of the stacking of the electrodes, not only all current output lugs, but also the corresponding electrically conductive outer side of the cell housing of the single cell or passes through it.
In an advantageous further development of the invention, the connection of the corresponding flat side of the cell housing, especially of an aluminum housing with copper foil as a pole, can be improved by inserting a foil of additional material, e.g., nickel.
According to an advantageous further development of the invention, the poles are only switched to the corresponding outer sides, especially flat sides of the cell housing with a welding process taking place at the end. Amongst others, a possible reduction of the installation space requirement results by the mentioned by means of variable contacting positions, a better contact cooling, a reduction of the parts by multi-functional component design insulation/housing etc., reduced reject numbers by a simple contacting at the closed cell housing. The production of hermetically closed cell housings is further eased, whereby the production of humidity-tight cell housings is connected amongst others.
Other objects, advantages and novel features of the present invention will become apparent from the following detailed description of the invention when considered in conjunction with the accompanying drawings.